the thing about that list is that the devs claimed halo series sold 40mil by May 2011. This was before Halo anniversary was released and with less than a year of halo reach sales. http://en.wikipedia.org/wiki/Halo_(series)#Reception_and_critical_response. Total Halo merchandise sales was $2bil at that time.

6mil+8mil+10mil+2mil+5mil+7mil=38mil.

This list is from after Anniversary got over 1.5mil, So its probably from January 2012 or later. By January 2012 total Halo merchandise sales were $2.8billion. Sales had gone up 800million dollars since May, and clearly Halo Anniversary didn't drive all those sales. There wasn't any halo movie, nor were there any extremly popular halo toys that came out. I have no idea about books though.

Edit

Also if these were current sales of Halo Reach, they would have included the 1mil+ digital bundles that came with consoles over the holidays. So that means Halo Reach only sold 6mil. Which is clearly wrong considering npd had it at close to 5mil in USA alone at September 2011.

I do think Reach is overtracked. NPD had it at around 5mil, September last year, while Vgchartz has it at 5.5mil by September in USA. The only physical bundles I'm aware of that came with phyiscal copies of Reach in USA are the limited edition consoles and I doubt that sold over 500k. So I'm assuming its 300k-400k overtracked in USA.

Also I think Halo 4 will only manage Halo Reach like sales. It should outsell it initially, but its legs will collapse when the nextbox comes out.

Unless nextbox don't have bc,i don't think it will impact Halo 4 sales,and maybe MS will re-launch the game but this time with nextbox logo to help nextbox sales

Next Generation will impact sales regardless of BC. A re-launch would help but some may count that as a seperate game.

Next-Gen wont affect Halo 4 all that much really as Halo in general has become more and more frontloaded over time.

Halo games still do have great legs, so a next gen would potentially cut off a lot of sales.

Did it impact Halo 2?

Yeah I know Halo actually has great legs and continues to sell for months, even years. But historically each new game does more of its sales in the 1st couple months. Halo 4 probably will be no exception and do the majority of its units in the first 4 months or so

I honestly don't know. Without VGC data that goes back that far, but if I had to guess, I'd say Halo 2's weekly sales slowed when the 360 released.

Yeah, but after the first year, they still sell another 2m or so on legs. For Halo 4, that 2m could be dropped dramatically because of the new gen.